PLEASE HELP ME ASAP!?!?!?!????? 20 POINTS

You and your friend each start a car-washing service.
You spend $25 on supplies and charge $10 per car.
Your friend spends $55 on supplies and charges $13 per car.
How many cars do you have to wash to earn the same amount of money as your
friend?
cars

y=10z-25
y=13z-55

_cars